Conventional optical filters having near infrared light absorption characteristics have been disclosed in Japanese Laid-Open Patent Application H6-118228 and elsewhere, in which the optical filter contains a phosphoric ester compound and an ionic metal component whose main component is copper ions.
A characteristic of this optical filter is that it efficiently absorbs near infrared light, but has high transmissivity to visible light, and is therefore used in applications that require the transmission of visible light and the blocking of near infrared light, such as thermal absorption members for windows, visibility correction filters, and display panels.